Cone/plate structured photothermal evaporator with obviously improved evaporation properties by suppressing thermal conduction-caused heat loss.

• Cone/plate structured evaporators have been designed for solar evaporation. • Cone/plate structures can effectively suppress thermal conduction-caused heat loss. • High evaporation rate of 2.21 kg m−2 h−1 with an efficiency of 131.4% was achieved. • High sea water evaporation capacity of 5.68 kg m−2 on a cloudy day was achieved. Solar-driven interfacial evaporation is a new and promising way to produce clean water. Suppression of heat loss is of great importance in solar-driven interfacial evaporators because it is the key to localizing solar-thermal energy. Up to date, most attention has been paid to suppressing heat loss by using materials with low thermal conductivity. Rare attention has been paid to suppressing heat loss by minimizing the contact area between photothermal conversion surfaces and other parts of evaporators, to the best of our knowledge. Herein, we develop a new design of cone/plate structure to suppress thermal conduction-caused heat loss by minimizing the contact area between photothermal film and its substrate. Under 1 sun illumination, the temperature gap between the top and side surfaces of a normal melamine foam evaporator is 12.3 °C, and it increases to 22.7 °C in a cone/plate structured evaporator, suggesting improved heat loss suppression and heat localization. In a normal melamine foam evaporator, an evaporation rate of 1.66 kg m−2 h−1 and a corresponding efficiency of 66.2% are obtained under 1 sun illumination. In the same condition, a high evaporation rate of 2.21 kg m−2 h−1 and a high corresponding efficiency of 131.4% can be achieved in a cone/plate structured evaporator. Meanwhile, cone/plate structured evaporators have high properties of dye water purification and seawater desalination. Simulated sea water evaporation tests show a high water evaporation capacity of 5.68 kg m−2 on a cloudy day, and the salinity in the condensed water (Na+ ions, 3.2 mg L−1) is below the WHO standards for drinkable water. Moreover, the cone/plate structured evaporator has low cost to produce, and can be easily scaled up for practical applications. [ABSTRACT FROM AUTHOR]